It costs $\$120$ to have a party for $9$ people at the skating rink. The cost includes a charge of $\$10$ for each person attending the party plus the price of a cake. How much does the cake cost? $\$$
Solution: $\text{Group cost}$ $\text{Cake}$ ${?}$ $9 \times 10$ ${120}$ $90$ There are $9$ people at the party and each paid $\$10$. We can multiply to find the cost for the people at the party. The cost for the party guests is $9\times\$10=\${90}$. ${\text{Total}}$ cost of the party $-$ costs of the ${\text{guests}}$ $=$ cost of the ${\text{cake}}$. ${120}-{90}={30}$ The cake is $\${30}$.